Universal Mobile Telecommunications System (UMTS) is one of the third-generation (3G) mobile telephone technologies (or 3rd Generation Wireless Mobile Communication Technology). A UMTS network consists of 1) a core network (CN), 2) a UMTS terrestrial radio access network (UTRAN) and 3) user equipment (UE). The core network provides routing, switching, and transit for user traffic. A Global System for Mobile Communications (GSM) network with General Packet Radio Service (GPRS) is the basic core network architecture that UMTS is based on. The UTRAN provides the air interface access method for User Equipment. A base station is referred to as Node B and control equipment for Node Bs is called a radio network controller (RNC). For an air interface, UMTS most commonly uses a wideband spread-spectrum mobile air interface known as wideband code division multiple access (or W-CDMA). W-CDMA uses a direct sequence code division multiple access signaling method (or CDMA) to separate users.
A UMTS Terrestrial Radio Access Network (UTRAN) is a collective term for the Node Bs (or base stations) and the control equipment for the Node Bs (or radio network controllers (RNC)) it contains which make up the UMTS radio access network. This is a 3G communications network which can carry both real-time circuit switched and IP based packet switched traffic types. The RNC provides control functionalities for one or more Node Bs. Connectivity is provided between the UE (user equipment) and the core network by the UTRAN.
The UTRAN is connected internally or externally to other functional entities by four interfaces: Iu, Uu, Iub and Iur. The UTRAN is attached to a GSM core network via an external interface called Iu. A radio network controller (RNC) supports this interface. In addition, the RNC manages a set of base stations called Node Bs through interfaces labeled Iub. The Iur interface connects two RNCs with each other. The UTRAN is largely autonomous from the core network since the RNCs are interconnected by the Iur interface. FIG. 1 discloses a communication system which uses the RNC, the Node Bs and the Iu and Uu interfaces. The Uu is also external and connects the Node B with the UE, while the Iub is an internal interface connecting the RNC with the Node B.
The RNC fills multiple roles. First, it may control the admission of new mobiles or services attempting to use the Node B. Second, from the Node B, i.e. base station, point of view, the RNC is a controlling RNC. Controlling admission ensures that mobiles are allocated radio resources (bandwidth and signal/noise ratio) up to what the network has available. It is where Node B's Iub interface terminates. From the UE, i.e. mobile, point of view, the RNC acts as a serving RNC in which it terminates the mobile's link layer communications. From the core network point of view, the serving RNC terminates the Iu for the UE. The serving RNC also controls the admission of new mobiles or services attempting to use the core network over its Iu interface.
In the UMTS system, universal terrestrial radio access (UTRA) frequency division duplex (FDD) channels and UTRA time division duplex (TDD) channels may be used to communicate data. The communication link through which the user equipment sends signals to the Node B is called an uplink. Applying interference cancellation in Node Bs will allow them to receive transmissions at higher data rates, i.e., interference cancellation can increase data rates on the uplink. It can also increase capacity on the uplink.
The apparatuses and methods of the present patent application is directed to overcoming limitations of the prior art and providing improved interference cancellation.